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RE: "Largest" dinosaurs...



> From: owner-dinosaur@usc.edu [mailto:owner-dinosaur@usc.edu]On Behalf Of
> Pluto77189@aol.com
>
>      I went ahead and looked up some info on the recent supposed
> "largest" dinosaurs: Giganotosaurs, carcaradontasaurs,
> Argintiniosaurus, etc...(I know I misspelled them).
>
> I am a bit frustrated about these claims.  It seems that they are
> based on WAY to fragmentary remains for such claims.  Even
> Spinosaurus, which remains SEEMED to be suggestive of a huge
> animal, were not really, ahhh...complete.

Surprise, surprise, surprise....

Well, I guess it really IS a surprise to a lot of people how incompletely
known some of the most famous dinosaurs are. (Even fewer people consider the
flip-side: how some very completely known taxa are so unknown to the general
public: "Dryosaurus: Wonder of the Jurassic" "A Day in the Life of
Gryposaurus", two titles you aren't going to see on documentaries...).

> I just find it difficult to put any credibility in these claims.
> With T-rex, we have sufficient remains to know--definitavly--how
> big any of the individuals was, at least in length, height, etc.

Exactly.

> Recent therapods claiming the BIGGER THAN T-REX!!!! status are
> doing so with only one or two fragmentary remains.
> I cannot see how any such claim can be taken seriously given the
> inability to accuratly extrapolate lengths from the complete
> remains of OTHER species using the FRAGMENTARY remains of "new"
> ones and scaling the up.--pardon the run-on.

It is true that some of the "bigger" theropods are known from very
fragmentary specimens, but the type of Giganotosaurus has a fair amount of
material, and a dentary exists which is even larger than the type.  Where
comparable bones are known, the Giganotosaurus specimens are larger than
those of the largest described T. rex material.  So unless you hypothesize
that the remaining bones of Gig. are proportionately smaller than that of
Tyrannosaurus, you're stuck with Giganotosaurus being larger than the tyrant
king.  (Note too that we are talking about individuals here: we have no real
grasp of the maximum size range of these guys, since we have statistically
insignificant numbers of specimens).

So known specimens of Giganotosaurus are bigger than known specimens of
Tyrannosaurus.  For the others, though, it is a LOT less certain.

Incidentally, a lot more of Gig. is known than is featured in detailed
photos in the original paper.

> I saw the skeletal reconstructions of argintiniosaurus( I think
> it was argintiniosaurs...) and Giganotosaurs mounted in a museam.
>  I Assumed that to do such an extensive reconstruction, much of
> the fossils were known.  I was wrong.

Indeed.

> I can't see how they justify the claim of a 100+ ton animal from
> a few bones.  The fossil record is too long and too varied to
> allow such scaling up any accuracy.

Best estimates for Argentinosaurus reflect that, saying it scales up between
80-100 tonnes.  Note that that you could comfortably fit three fully grown
T. rex in that range of uncertainty!!


                Thomas R. Holtz, Jr.
                Vertebrate Paleontologist
Department of Geology           Director, Earth, Life & Time Program
University of Maryland          College Park Scholars
                College Park, MD  20742
http://www.geol.umd.edu/~tholtz/tholtz.htm
http://www.geol.umd.edu/~jmerck/eltsite
Phone:  301-405-4084    Email:  tholtz@geol.umd.edu
Fax (Geol):  301-314-9661       Fax (CPS-ELT): 301-405-0796